The invention relates generally to devices for correcting fractures or the like. It relates specifically to such a device adapted to enable substantially-anatomic reduction of a posteriorly unstable pelvic disruption.
The prior art includes pins for use in reducing bone disruptions, as in U.S. Pat. Nos. 4,175,555 and 3,977,138. Such pins include threaded ends for enabling tapping thereof into portions of the bone in which the disruption has occured, at locations spaced about the disrupted surfaces.
Such pins are adapted to enable holding of the portions of the disrupted bone to which they are secured, in compressive engagement, for reducing the fracture. However, such pins are not adapted to enable secure fixation thereof for securely holding portions of a large bone, as the posterior pelvis, in compressive engagement, to enable reduction of a posteriorly unstable pelvic fracture
The prior art further includes frames for use in reducing bone fractures or disruptions, as in U.S. Pat. Nos. 2,250,417 and 4,398,898. However, such frames are likewise not adapted for use in reducing fractures of large bones, as the posterior pelvis.
The prior art still further includes frames adapted for use in reducing pelvic fractures, as in U.S. Pat. Nos. 4,361,144, 4,024,860, and 4,185,623. However, such frames are secureable to the anterior pelvis, a relatively small non-weight bearing portion of the pelvic bone. Further, such frames require a multiplicity of relatively thin pins for securing thereof to the anterior pelvis, and include complex and inefficient mechanisms for applying compressive force therethrough to the fractured bone for reducing the fracture.
Further, such anterior frames are adapted for use in reducing pelvic disruptions where satisfactory stability may be achieved by anterior pelvic fixation, as where supporting ligaments are functionally intact and where there is no posterior instability. Such frames and pins are further generally not strong enough to permit prompt patient ambulation and sitting, thereby requiring prolonged patient bed rest and immobilization, with- resulting problems of increased patient susceptibility to complications, and loss of effective reduction with subsequent malunion of disrupted surfaces.
The posterior pelvis is a relatively large weight-bearing portion of the pelvic bone, which transmits proximal weight to the lower limbs. A fracture or dislocation of the posterior pelvis can result in instability in a displacement pattern in a plurality of planes as well as in a rotary direction Thus, posterior pelvic fractures or dislocations are best stabilized and reduced posteriorly, where the frame and pins are proximate to the site of instability and where greater rigidity of fixation may be achieved.
Anterior frames and pins are ineffective in reducing such posterior pelvic fractures, as such frames and pins are remote from the site of the posterior fracture or dislocation, and are not securely affixable thereto. Further, compression applied through such anterior frames in the frontal plane may result in tension and opening of the posterior pelvic fracture, due to the point of application of compressive force relative to the center of rotation of the disrupted posterior pelvic rim.
Still further, such anterior frames and pins are primarily adapted to retain an executed reduction in place, so as to maintain such a reduction already attained, and are generally not capable of providing secure fixation and substantially-anatomic alignment and uniting of surfaces for proper reduction of an unstable posterior pelvic disruption.